JPH1112308A - Polymerization of propylene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain polypropylene in high yield by using a homogeneous catalyst comprising a carried catalyst component and an organometallic compound soluble in propylene, polymerizing propylene, as the propylene itself is used as a liquid medium, washing the resultant slurry with propylene to recycle the washing solution to the polymerization area and separating propylene from the slurry by evaporation. SOLUTION: In a preferred embodiment, a homogeneous catalyst comprising an aluminoxane-carrying carrier catalyst component as dimethylsilyl-bis(cyclopentadienyl)zirconium dichloride, etc., and an organometallic compound soluble in propylene as trimethyl aluminum, etc., is used to polymerize propylene by using propylene itself as a liquid medium. The polymerization system comprises the polymerization area and the slurry-washing area, the resultant polymer slurry is washed with propylene, the washing liquid is circulated to the polymerization area, while propylene is evaporated off from the washed slurry thereby producing polypropylene in high yield with the use of the organometallic compound reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for polymerizing propylene. More specifically, it relates to a method for continuously polymerizing propylene using a homogeneous catalyst under specific polymerization conditions.

[0002]

2. Description of the Related Art As a method for polymerizing propylene using a homogeneous catalyst, it is the first to disclose a method for polymerizing ethylene using zirconocene and methylaluminoxane. It has been reported that crystalline polypropylene such as isotactic and syndiotactic polypropylene can be obtained by using a metallocene compound having a ligand to which two cyclopentadienyl groups or derivatives thereof are bonded (Journal of the Rubber Association of Japan) Vol. 69, No. 161). When these homogeneous catalysts are used, it is possible to obtain polymers whose composition is uniform and whose molecular weight distribution is freely controlled from a narrow one to a wide one, and it is expected that polymers with unprecedented physical properties will be obtained. Is done.

[0003]

The use of a homogeneous catalyst does not produce an aggressive polymer if the composition is uniform and the catalyst system is pure, but it is preferable to remove the components used as the catalyst. However, when the slurry is washed to remove the organometallic compound, even if the washing conditions are strictly controlled, not only the intended organometallic compound but also the polymer fine powder entrains the washing solution side, and if the monomer is recovered from the washing system, it becomes non-volatile. There is a problem that fine powder remains as a part and it is difficult to handle it.

An object of the present invention is to provide a method for stably polymerizing propylene at a high yield per catalyst with a very small amount of an organometallic compound used.

[0005]

Means for Solving the Problems The present inventors have diligently studied a method for efficiently producing polypropylene by solving the above problems and completed the present invention.

That is, in the method for polymerizing propylene of the present invention, a homogeneous catalyst is used in a method of stereoregularly polymerizing propylene in a polymerization system comprising a polymerization zone and a slurry washing zone using propylene itself as a liquid medium. Using a catalyst consisting of a supported catalyst component and a propylene-soluble organometallic compound, the obtained polymerization slurry is washed with propylene, the washing liquid is returned to the polymerization zone, and propylene is evaporated from the washed slurry to obtain polypropylene. It is characterized by the following.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, polymerization is carried out by a bulk polymerization method using propylene itself as a liquid medium. In the bulk polymerization method, an expensive homogeneous catalyst having a high monomer concentration can be effectively used.

The homogeneous catalyst has a relatively high activity, but it is important to increase the amount of polypropylene produced per transition metal catalyst component. A compound which is stable at a relatively high temperature is preferably used. Used on a carrier to maintain good properties.

The transition metal compound component used in the present invention and used in the homogeneous catalyst is not limited as long as propylene is stereoregularly polymerized to give a crystalline polypropylene, but it is Cl-symmetric or Cs-symmetric. A zirconium, hafnium, or titanium complex is used, and specific examples include a compound having a ligand having a structure in which two cyclopentadienyl groups or derivatives thereof are bonded. Examples of these include dimethylsilylbis (cyclopentadienyl) zirconium dichloride, dimethylsilylbis (tetramethylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (methylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (dimethyl Cyclopentadienyl) zirconium dichloride, dimethylsilyl (2,4-dimethylcyclopentadienyl) (3 ′, 5′-dimethylcyclopentadienyl) zirconium dichloride, dimethylsilyl (2,3,5-trimethylcyclopentadiyl) Enil)
(2 ′, 4 ′, 5′-trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (t
-Butylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (trimethylsilylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (2-trimethylsilyl-4-t-butylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (4 5,6,7-tetrahydro-indenyl)
Zirconium dichloride, dimethylsilylbis (indenyl) zirconium dichloride, dimethylsilylbis (2-methylindenyl) zirconium dichloride, dimethylsilylbis (2,4-dimethylindenyl) zirconium dichloride, dimethylsilylbis (2,4,7
-Trimethylindenyl) zirconium dichloride, dimethylsilylbis (2-ethyl-4-phenylindenyl) zirconium dichloride, dimethylsilylbis (2
-Ethyl-4-phenylindenyl) zirconium dichloride, dimethylsilylbis (benz [e] indenyl) zirconium dichloride, dimethylsilylbis (2
-Methylbenz [e] indenyl) zirconium dichloride, dimethylsilylbis (3-methylbenz [e] indenyl) zirconium dichloride, dimethylsilylbis (benz [f] indenyl) zirconium dichloride, dimethylsilylbis (2-methylbenz [f] indenyl) Zirconium dichloride, dimethylsilylbis (3-methylbenz [f] indenyl) zirconium dichloride, dimethylsilylbis (cyclopentane [cd]
Indenyl) zirconium dichloride, dimethylsilylbis (cyclopentadienyl) zirconium dimethyl,
Dimethylsilylbis (tetramethylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (methylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (dimethylcyclopentadienyl) zirconium dimethyl, dimethylsilyl (2,4-dimethylcyclopenta Dienyl) (3 ', 5'-dimethylcyclopentadienyl) zirconium dimethyl, dimethylsilyl (2,3,5-trimethylcyclopentadienyl)
(2 ′, 4 ′, 5′-trimethylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (t-
Butylcyclopentadienyl) zirconium dimethyl,
Dimethylsilylbis (trimethylsilylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (2-trimethylsilyl-4-t-butylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (4,5,6, -tetrahydro-indenyl) zirconium Dimethyl, dimethylsilylbis (indenyl) zirconium dimethyl, dimethylsilylbis (2-methylindenyl) zirconium dimethyl, dimethylsilylbis (2,4-dimethylindenyl) zirconium dimethyl, dimethylsilylbis (2,4,7-trimethyl Indenyl) zirconium dimethyl, dimethylsilylbis (2-methyl-4-phenylindenyl) zirconium dimethyl, dimethylsilylbis (2-ethyl-4-phenylindenyl) zirco Dimethyl, dimethylsilylbis (benz [e] indenyl) zirconium dimethyl, dimethylsilylbis (2-methylbenz [e] indenyl) zirconium dimethyl, dimethylsilylbis (3-methylbenz [e] indenyl) zirconium dimethyl, dimethylsilylbis (benz) [F] indenyl) zirconium dimethyl, dimethylsilylbis (2-
Methylbens [f] indenyl) zirconium dimethyl, dimethylsilylbis (3-methylbenz [f] indenyl) zirconium dimethyl, dimethylsilylbis (cyclopenta [cd] indenyl) zirconium dimethyl, etc. and zirconium of the above metallocene compound was replaced by titanium or hafnium Metallocene compounds and the like.

[0010] Alternatively, isopropylidene (cyclopentadienyl-fluorenyl) zirconium dichloride,
Isopropylidene (cyclopentadienyl-indenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-2,7-di-t-butylfluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-3-methylfluoride) Nil) zirconium dichloride, isopropylidene (cyclopentadienyl-4-methylfluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-oftahydrofluorenyl) zirconium dichloride, isopropylidene (methylcyclopentadienyl-fluorenyl) ) Zirconium dichloride, isopropylidene (dimethylcyclopentadienyl-fluorenyl) zirconium dichloride, isopropylidene (tetramethylcyclopentadienyl-phenyl) Oreniru) zirconium dichloride or isopropylidene group is diphenylmethylene group, cyclohexylidene group, methylphenylmethylene group, those having a structure in which a dimethylsilylene group or the like which dichloride became dimethyl, and the like.

Further, ethylenebis (indenyl) zirconium dichloride, ethylenebis (4,5,6,7
-Tetrahydroindenyl) zirconium dichloride,
1,2-dimethylethylidyl-1,2-bis (indenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (2′-methylindenyl) zirconium dichloride, 1,2-diisopropyl Ethyridyl-1,2-bis (indenyl) zirconium dichloride, 1,2-diisopropylethyldiyl-1,2
-Bis (2′-methylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (3′-methylindenyl) zirconium dichloride,
1,2-dimethylethylidyl-1,2-bis (4′-
Isopropylindenyl) zirconium dichloride,
1,2-dimethylethylidyl-1,2-bis (4 ′,
7'-diisopropylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (2'-methyl-4'-isopropylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-
1,2-bis (4′-cyclohexylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-
1,2-bis (2′-methyl-4′-cyclohexylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (4′-phenylindenyl) zirconium dichloride, 1,2- Dimethylethylidyl-1,2-bis (4 ', 7'-diphenylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (2'-methyl-4'-phenylindenyl) ) Zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (4′-naphthylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (2′-methyl-4) '-Naphthylindenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (5'-phenylindenyl) zirconium dichloride 1,2-dimethylethylidyl-1,2-bis (4'-methoxyindenyl) zirconium dichloride, 1,2-dimethylethylidyl, -1,2-bis (benz [e] indenyl) zirconium dichloride , 1,2-dimethylethylidyl-1,2-bis (2'-methylbenz [e] indenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (3'-methylbenz [e] Indenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (benz [f] indenyl)
Zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (2′-methylbenz [f] indenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (3′-methylbenz [ f] indenyl) zirconium dichloride, 1,2-dimethylethylidyl-1,2-bis (cyclopenta [cd] indenyl) zirconium dichloride and the like.

In the present invention, a carrier in which an inactive compound supports a compound that forms a stable anion upon contact with an aluminoxane or a transition metal catalyst component can be used. The transition metal catalyst component may be supported in advance, may be supported immediately before the polymerization, or may be separately introduced into the polymerization zone.

As the inert compound, inorganic oxides such as silica, alumina, magnesia, sodium oxide, lithium oxide or composite oxide, magnesium chloride,
Examples thereof include metal chlorides such as calcium chloride and various polymers, particularly polymers having functional groups such as ethers, esters, carboxylic acids, and alcohols. In particular, those obtained by graft-polymerizing monomers having various functional groups on polypropylene are preferably used.

As the aluminoxane, the following general formula (1):

[0015]

Embedded image Alternatively, a compound represented by the general formula (2) is used.

[0016]

Embedded image (In the formula, R ³ may be the same or different and is an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 18 carbon atoms, or hydrogen, and p is an integer of 2 to 50, preferably 10 to 35. The use ratio of the aluminoxane represented by the above general formula to the above metallocene compound is generally from 1 to 10,000 mol times as aluminum / metallocene, preferably from 10 to 1,000. This aluminoxane is used by being supported on an inert carrier.

In the present invention, the compound that forms a stable anion species is a compound that converts the above-mentioned transition metal compound into a cationic compound and generates a stable counter anion species. Specifically, a compound that forms a stable anionic species with the above transition metal compound and an organometallic compound described below are used in combination. Specific examples of compounds that form stable anionic species include triphenylcarbenium tetrakis (pentafluorophenyl) borate, ferrocenium tetrakis (pentafluorophenyl) borate,
N, N-dimethylammonium tetrakis (pentafluorophenyl) borate, tri-n-butylammonium tetrakis (pentafluorophenyl) borate, triethylammonium tetratetrakis (phenyl) borate, tri-n-butylammonium tetra (phenyl)
Examples include carbenium borane such as borate, metalabran, and ammonium borane.
These are exemplified in, for example, JP-A-501950 and JP-A-1-502036. The ratio of the compound forming these stable anionic species to the transition metal compound is 0.1 to 10 as the ionic compound / transition metal compound.
It is molar times. The ratio of the organometallic compound to the transition metal compound to be described later is 1 to 10,000 mole times as organometallic compound / transition metal compound.

As the organometallic compound soluble in propylene, the metal is selected from the first, second, twelve and twelve groups of the periodic table.
An alkyl metal compound selected from Group 3 and specifically lithium, sodium, potassium, or beryllium, magnesium, or zinc, cadmium, or an organometallic compound including aluminum, gallium, and an alkyl having 1 to 20 carbon atoms. . Particularly preferably, it has 1 carbon atom.
~ 20 alkyl aluminum compounds. Examples of such an organoaluminum compound include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, and tri-n-aluminum.
Butylaluminum, triisobutylaluminum, trisec-butylaluminum, dimethylaluminum chloride, diethylaluminum chloride, di-n-propylaluminum chloride, diisopropylaluminum chloride, din-butylaluminum chloride, diisobutylaluminum chloride, disec-butylaminiumchloride And the like, particularly preferably trimethylamylnium, triethylaluminum, tri-n-
Propylaluminum, triisopropylaluminum, trin-butylaluminum, triisobutylaluminum, and trisec-butylaluminum.

The amount of the transition metal compound and the term transition metal compound soluble in propylene is determined by the ratio of the number of moles of the organometallic compound to the number of moles of the transition metal of the organic transition metal compound (organometallic compound / transition metal). As 1 to 10000,
Preferably it is 10-1000.

In the present invention, the polymerization of propylene is not limited to homopolymerization of propylene, but also a small amount of other olefins, specifically α-olefins having 2 to 20 carbon atoms (excluding propylene), preferably 2 to 10 α carbon atoms. Copolymerization of olefins (including ethylene), that is, ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, vinylcyclohexane, styrene and the like can do. Further, butadiene, 1,4-pentadiene, 1,5
-Carbon number 4 such as hexadiene and 1,4-hexadiene
~ 20 diene, or cyclic olefins such as dicyclopentadiene, norbornene, methylnorbornene, tetracyclododecene, methyltetracyclododecene, or silicon-containing olefins such as allyltrimethylsilane and vinyltrimethylsilane. It can be exemplified as a monomer. The amount of the monomer to be copolymerized is not particularly limited as long as the obtained polymer is crystalline, but is generally 40% by weight or less in the polymer. The method of copolymerization is not particularly limited, and random copolymerization and block copolymerization are possible. Here, during block copolymerization, the washing liquid of the slurry is generally returned to the copolymerization section, and homopolymerization or randomization that can be returned to the beginning of the polymerization zone in terms of effective use of the organometallic compound is performed. It is more effective to apply to polymerization.

In the present invention, there is no particular limitation on the method for washing the slurry with propylene, and the method for washing by filtration is:
Although there is a method of countercurrent cleaning and the like, countercurrent cleaning is simple in terms of cleaning efficiency and cleaning under high pressure.

[0022]

The present invention will be further described below with reference to examples, but the present invention is not limited to these examples.

In the present invention, the melting point (Tm) and intrinsic viscosity ([η]) were measured by the following methods. Melting point (Tm): The melting point (Tm) measured by differential scanning calorimetry (DSC) was measured under the following conditions. [measuring device:
Perkin Elmer DSC-4, heating rate: 10 ° C / mi
n, temperature drop rate: -10 ° C / min, or -30 ° C / m
in]. -Intrinsic viscosity ([η]) The viscosity was measured with a tetralin solution at 135 ° C. Comparative Example 1 Polymerization was carried out using a reactor having the shape shown in FIG.
The homogeneous catalyst was synthesized by a conventional method as a transition metal compound component. Using diphenylmethylene (cyclopentadienyl-fluorenyl) zirconium dichloride, triisobutylaluminum as an organometallic compound component, methylaluminoxane (manufactured by Albemarle) as a carrier, and maleic anhydride grafted on polypropylene (Mitsui Toatsu Chemicals, Inc. Co., Ltd. (trade name Ron Ply),
What was supported on maleic anhydride content 6.64% by weight, 0.68 mmol / g-GPP (28.8 g of methylaluminoxane and 20 g of GPP) were mixed at 140 ° C. in 4200 ml of xylene, and the temperature was lowered to 20 ° C. Was separated and dried, and further pulverized into fine pieces.). (Pretreatment of homogeneous catalyst component) In an autoclave having an internal volume of 200 L (liter), 120 L of heptane, 21.5 g of triisobrityl aluminum, and diphenylmethylene (cyclopentadienyl- as a transition metal compound component) were used.
1.0 g of fluorenyl) zirconium dichloride, 120 g of the above solid catalyst component were charged, and then 1200 g of propylene was charged while maintaining the internal temperature at 25 ° C., and reacted for 2 hours.
This was a pretreatment catalyst component slurry. When a part was sampled and analyzed, this solid catalyst component contained 0.13% by weight of zirconium, and 9 g per solid catalyst.
Was polymerized. (Polymerization reaction) Referring to FIG. 1, 84.6 kg / hour of propylene and 60.2 NL / hour in a state where hydrogen was dissolved in propylene in an annular reactor 1 having an inner volume of 60 L, and the above pretreated catalyst component as a catalyst The slurry was used as a solid catalyst component in an amount of 5.19 g / hour and triisobutylaluminum 6.1.
At a rate of 3 g / hour, the slurry was polymerized while circulating the slurry with a slurry circulation pump 5 in a full state without a gas phase. The temperature of the annular reactor 1 is 45 ° C. and the pressure is 3
3 kg / cm ² -G, and the polymer yield per transition metal compound in this polymerization region calculated from the material balance was ² kg.
It was 7.1 kg-PP / mmol transition metal catalyst component. The obtained slurry was continuously sent to a polymerization machine 2 having an internal volume of 1000 L to further polymerize. Propylene is supplied to the polymerization machine 2 at a rate of 50.6 kg / hour, the temperature is 70 ° C., and the pressure is 3
0 kg / cm ² -G, and the hydrogen concentration in the gas phase is 1.7
It was supplied so as to be adjusted to mol%. The obtained slurry was continuously fed to a polymerization machine 3 having an internal volume of 500 L by a slurry circulation pump 5A, and was further polymerized. Propylene is supplied to the polymerization machine 3 at a rate of 11.2 kg / hour and the temperature is 68
C., a pressure of 29 kg / cm ² -G, and hydrogen were supplied and adjusted so that the hydrogen concentration in the gas phase became 1.7 mol%. The slurry exiting the polymerization machine 3 is continuously fed to the upper part of the countercurrent washing tower 4 by a slurry circulation pump 5B, and propylene for washing is supplied at a rate of 145.2 kg / hour from the lower part of the tower. It was withdrawn at 141.6 kg / hour. The washing liquid extracted from the upper part of the tower was introduced into a heated double pipe through steam to recover unreacted monomer from the washing liquid. However, the double pipe was clogged by the fine powder of polymer accompanying the washing liquid, so that the washing liquid was transferred to the flash tank. Switched. Further, the washed slurry was taken out from the lower part of the tower, alcohol was added thereto to deactivate the same, and after removing unreacted monomers, the polymerization powder was recovered. The powder was obtained at 60 kg / h. The powder obtained is 80
It dried at 60 degreeC and 60 mmHg for 10 hours, and was set as the product. The yield of polymer per transition metal compound calculated from the material balance was 773 kg-PP / mmol transition metal catalyst component, [η] of the product powder was 1.41 dl / g, and Tm was 134.3 ° C. Example 1 Washing efficiency in the countercurrent washing tower 4 is 85% (the ratio of triisobutylaluminum in the washing liquid extracted from the upper part of the tower to triisobutylaluminum in the slurry extracted from the lower part of the tower is (85:15)) The amount of propylene for washing introduced from the lower part of the column was set to 77 kg / hour so that the washing liquid extracted from the upper part of the column was returned to the annular reactor 1 in an amount of 73.5 kg / hour. The same procedure as in Comparative Example 1 was carried out except that the amount of introduced propylene was reduced to 11.1 kg / hour and the amount of triisobutylaluminum was reduced to 0.92 g / hour.
The polymer yield per transition metal compound calculated from the mass balance was 768 kg-PP / mmol transition metal catalyst component, and the product powder [η] was 1.3.
9 dl / g, Tm was 134.5 ° C., and a polymer similar to that of Comparative Example 1 was obtained. By returning the washing liquid extracted from the upper part of the countercurrent washing tower to the polymerization zone, 1 / 6.7 of the method for recovering only propylene as a volatile matter from the washing liquid.
The polymerization proceeds with triisobutylaluminum. Comparative Example 2 Comparative Example 1
The procedure of Comparative Example 1 was repeated except that the ratio was changed to 1 / 6.7. As a result, only 29.4 kg / hour of the polypropylene powder was obtained, and the melting point was as low as 129.5 ° C.

[0024]

Industrial Applicability By carrying out the method of the present invention, it is possible to produce polypropylene in a high yield per catalyst stably with an extremely small amount of an organometallic compound, which is extremely valuable industrially. . This is because the present polymerization system does not use a third component such as an electron donor and all other catalyst components are supported on a carrier, so that impurities and reaction products do not accumulate in the system. Presumed.

[Brief description of the drawings]

FIG. 1 is a flow sheet for explaining an example of a method suitable for carrying out the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cyclic reactor 2, 3 Polymerizer 4 Countercurrent washing tower 5, 5A, 5B Pump for slurry circulation

Continued on the front page (72) Inventor Harima, 1-6-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Chemicals Co., Ltd.

Claims (2)

[Claims] 1. A method for stereoregularly polymerizing propylene in a polymerization system comprising a polymerization zone and a slurry washing zone using propylene itself as a liquid medium using a homogeneous catalyst, wherein the homogeneous catalyst is soluble in a supported catalyst component and propylene. The polymerization of propylene is characterized in that the polymerization slurry obtained is washed with propylene using a catalyst composed of an organic metal compound, the washing liquid is returned to the polymerization zone, and propylene is evaporated from the washed slurry to obtain polypropylene. Method. 2. The method according to claim 1, wherein the homogeneous catalyst comprises a component in which aluminoxane is supported on a polymer.